Maven Project

To learn how to set up the Maven project for Spring Cloud Contract Verifier, read the following sections:

Adding the Maven Plugin
Maven and Rest Assured 2.0
Using Snapshot and Milestone Versions for Maven
Adding stubs
Run Plugin
Configure plugin
Configuration Options
Single Base Class for All Tests
Using Different Base Classes for Contracts
Invoking Generated Tests
Pushing Stubs to SCM
Maven Plugin and STS

You can also check the plugin’s documentation here.

1. Adding the Maven Plugin

To add the Spring Cloud Contract BOM, include the following section in your pom.xml file:

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-contract-dependencies</artifactId>
    <version>${spring-cloud-contract.version}</version>
    <type>pom</type>
    <scope>import</scope>
</dependency>

Next, add the Spring Cloud Contract Verifier Maven plugin, as follows:

            <plugin>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-contract-maven-plugin</artifactId>
                <version>${spring-cloud-contract.version}</version>
                <extensions>true</extensions>
                <configuration>
                    <packageWithBaseClasses>com.example.fraud</packageWithBaseClasses>
<!--                    <convertToYaml>true</convertToYaml>-->
                </configuration>
            </plugin>

You can read more in the spring-cloud-contract-maven-plugin/index.html[Spring Cloud Contract Maven Plugin Documentation].

Sometimes, regardless of the picked IDE, you can see that the target/generated-test-source folder is not visible on the IDE’s classpath. To ensure that it is always there, you can add the following entry to your pom.xml

<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>build-helper-maven-plugin</artifactId>
    <executions>
        <execution>
            <id>add-source</id>
            <phase>generate-test-sources</phase>
            <goals>
                <goal>add-test-source</goal>
            </goals>
            <configuration>
                <sources>
                    <source>${project.build.directory}/generated-test-sources/contracts/</source>
                </sources>
            </configuration>
        </execution>
    </executions>
</plugin>

2. Maven and Rest Assured 2.0

By default, Rest Assured 3.x is added to the classpath. However, you can use Rest Assured 2.x by adding it to the plugins classpath, as follows:

<plugin>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-contract-maven-plugin</artifactId>
    <version>${spring-cloud-contract.version}</version>
    <extensions>true</extensions>
    <configuration>
        <packageWithBaseClasses>com.example</packageWithBaseClasses>
    </configuration>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-contract-verifier</artifactId>
            <version>${spring-cloud-contract.version}</version>
        </dependency>
        <dependency>
           <groupId>com.jayway.restassured</groupId>
           <artifactId>rest-assured</artifactId>
           <version>2.5.0</version>
           <scope>compile</scope>
        </dependency>
        <dependency>
           <groupId>com.jayway.restassured</groupId>
           <artifactId>spring-mock-mvc</artifactId>
           <version>2.5.0</version>
           <scope>compile</scope>
        </dependency>
    </dependencies>
</plugin>

<dependencies>
    <!-- all dependencies -->
    <!-- you can exclude rest-assured from spring-cloud-contract-verifier -->
    <dependency>
       <groupId>com.jayway.restassured</groupId>
       <artifactId>rest-assured</artifactId>
       <version>2.5.0</version>
       <scope>test</scope>
    </dependency>
    <dependency>
       <groupId>com.jayway.restassured</groupId>
       <artifactId>spring-mock-mvc</artifactId>
       <version>2.5.0</version>
       <scope>test</scope>
    </dependency>
</dependencies>

That way, the plugin automatically sees that Rest Assured 2.x is present on the classpath and modifies the imports accordingly.

3. Using Snapshot and Milestone Versions for Maven

To use Snapshot and Milestone versions, you have to add the following section to your pom.xml:

<repositories>
    <repository>
        <id>spring-snapshots</id>
        <name>Spring Snapshots</name>
        <url>https://repo.spring.io/snapshot</url>
        <snapshots>
            <enabled>true</enabled>
        </snapshots>
    </repository>
    <repository>
        <id>spring-milestones</id>
        <name>Spring Milestones</name>
        <url>https://repo.spring.io/milestone</url>
        <snapshots>
            <enabled>false</enabled>
        </snapshots>
    </repository>
    <repository>
        <id>spring-releases</id>
        <name>Spring Releases</name>
        <url>https://repo.spring.io/release</url>
        <snapshots>
            <enabled>false</enabled>
        </snapshots>
    </repository>
</repositories>
<pluginRepositories>
    <pluginRepository>
        <id>spring-snapshots</id>
        <name>Spring Snapshots</name>
        <url>https://repo.spring.io/snapshot</url>
        <snapshots>
            <enabled>true</enabled>
        </snapshots>
    </pluginRepository>
    <pluginRepository>
        <id>spring-milestones</id>
        <name>Spring Milestones</name>
        <url>https://repo.spring.io/milestone</url>
        <snapshots>
            <enabled>false</enabled>
        </snapshots>
    </pluginRepository>
    <pluginRepository>
        <id>spring-releases</id>
        <name>Spring Releases</name>
        <url>https://repo.spring.io/release</url>
        <snapshots>
            <enabled>false</enabled>
        </snapshots>
    </pluginRepository>
</pluginRepositories>

4. Adding stubs

By default, Spring Cloud Contract Verifier looks for stubs in the src/test/resources/contracts directory. The directory containing stub definitions is treated as a class name, and each stub definition is treated as a single test. We assume that it contains at least one directory to be used as the test class name. If there is more than one level of nested directories, all except the last one is used as the package name. Consider the following structure:

src/test/resources/contracts/myservice/shouldCreateUser.groovy
src/test/resources/contracts/myservice/shouldReturnUser.groovy

Given that structure, Spring Cloud Contract Verifier creates a test class named defaultBasePackage.MyService with two methods:

shouldCreateUser()
shouldReturnUser()

5. Run Plugin

The generateTests plugin goal is assigned to be invoked in the phase called generate-test-sources. If you want it to be part of your build process, you need not do anything. If you want only to generate tests, invoke the generateTests goal.

If you want to run stubs from Maven, call the run goal with the stubs to run as the spring.cloud.contract.verifier.stubs system property as follows:

mvn org.springframework.cloud:spring-cloud-contract-maven-plugin:run \ -Dspring.cloud.contract.verifier.stubs="com.acme:service-name"

6. Configure plugin

To change the default configuration, you can add a configuration section to the plugin definition or the execution definition, as follows:

<plugin>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-contract-maven-plugin</artifactId>
    <executions>
        <execution>
            <goals>
                <goal>convert</goal>
                <goal>generateStubs</goal>
                <goal>generateTests</goal>
            </goals>
        </execution>
    </executions>
    <configuration>
        <basePackageForTests>org.springframework.cloud.verifier.twitter.place</basePackageForTests>
        <baseClassForTests>org.springframework.cloud.verifier.twitter.place.BaseMockMvcSpec</baseClassForTests>
    </configuration>
</plugin>

7. Configuration Options

testMode: Defines the mode for acceptance tests. By default, the mode is MockMvc, which is based on Spring’s MockMvc. You can also change it to WebTestClient, JaxRsClient, or Explicit (for real HTTP calls).
basePackageForTests: Specifies the base package for all generated tests. If not set, the value is picked from the package of baseClassForTests and from packageWithBaseClasses. If neither of these values are set, the value is set to org.springframework.cloud.contract.verifier.tests.
ruleClassForTests: Specifies a rule that should be added to the generated test classes.
baseClassForTests: Creates a base class for all generated tests. By default, if you use Spock classes, the class is spock.lang.Specification.
contractsDirectory: Specifies a directory that contains contracts written with the Groovyn DSL. The default directory is /src/test/resources/contracts.
generatedTestSourcesDir: Specifies the test source directory where tests generated from the Groovy DSL should be placed. By default, its value is $buildDir/generated-test-sources/contracts.
generatedTestResourcesDir: Specifies the test resource directory for resources used by the generated tests.
testFramework: Specifies the target test framework to be used. Currently, Spock, JUnit 4 (TestFramework.JUNIT), and JUnit 5 are supported, with JUnit 4 being the default framework.
packageWithBaseClasses: Defines a package where all the base classes reside. This setting takes precedence over baseClassForTests. The convention is such that, if you have a contract under (for example) src/test/resources/contract/foo/bar/baz/ and set the value of the packageWithBaseClasses property to com.example.base, Spring Cloud Contract Verifier assumes that there is a BarBazBase class under the com.example.base package. In other words, the system takes the last two parts of the package, if they exist, and forms a class with Base as a suffix.
baseClassMappings: Specifies a list of base class mappings that provide contractPackageRegex (which is checked against the package where the contract is located) and baseClassFQN( which maps to the fully qualified name of the base class for the matched contract). For example, if you have a contract under src/test/resources/contract/foo/bar/baz/ and map the .* → com.example.base.BaseClass property, the test class generated from these contracts extends com.example.base.BaseClass. This setting takes precedence over packageWithBaseClasses and baseClassForTests.
contractsProperties: A map that contains properties to be passed to Spring Cloud Contract components. Those properties might be used by (for example) built-in or custom Stub Downloaders.
failOnNoContracts: When enabled, will throw an exception when no contracts were found. Defaults to true.
failOnInProgress: If set to true, then, if any contracts that are in progress are found, they break the build. On the producer side, you need to be explicit about the fact that you have contracts in progress and take into consideration that you might be causing false positive test results on the consumer side. Defaults to true.
incrementalContractTests: When enabled, tests are created only when contracts have changed since last build. Defaults to true.
incrementalContractStubs: When enabled, stubs are created only when contracts have changed since last build. Defaults to true.
incrementalContractStubsJar: When enabled, stubs jar is created only when stubs have changed since last build. Defaults to true. *httpPort : HTTP port for the WireMock server that serves stubs. Currently spring.cloud.contract.verifier.http.port property works only when serving stubs from the directory. Otherwise, when providing stubs id, port have to be included in the id string. *skip: Set this to true to bypass the verifier execution. *skipTestOnly: Set this to true to bypass verifier test generation. *stubs : List of stubs to be downloaded and ran in a colon separated Ivy notation. *minPort : Specifies the minimal port at which the stub should start. *maxPort : Specifies the maximal port at which the stub should start. *waitForKeyPressed : Specifies if the plugin should wait for the user to press the key after starting the stubs. *stubsClassifier: Specifies the classifier used by stubs artifacts.

If you want to download your contract definitions from a Maven repository, you can use the following options:

contractDependency: The contract dependency that contains all the packaged contracts.
contractsPath: The path to the concrete contracts in the JAR with packaged contracts. Defaults to groupid/artifactid where gropuid is slash separated.
contractsMode: Picks the mode in which stubs are found and registered.
deleteStubsAfterTest: If set to false, do not remove any downloaded contracts from temporary directories.
contractsRepositoryUrl: URL to a repository with the artifacts that have contracts. If it is not provided, use the current Maven ones.
contractsRepositoryUsername: The user name to be used to connect to the repo with contracts.
contractsRepositoryPassword: The password to be used to connect to the repo with contracts.
contractsRepositoryProxyHost: The proxy host to be used to connect to the repo with contracts.
contractsRepositoryProxyPort: The proxy port to be used to connect to the repo with contracts.

We cache only non-snapshot, explicitly provided versions (for example + or 1.0.0.BUILD-SNAPSHOT do not get cached). By default, this feature is turned on.

The following list describes experimental features that you can turn on in the plugin:

convertToYaml: Converts all DSLs to the declarative YAML format. This can be extremely useful when you use external libraries in your Groovy DSLs. By turning this feature on (by setting it to true), you need not add the library dependency on the consumer side.
assertJsonSize: You can check the size of JSON arrays in the generated tests. This feature is disabled by default.

8. Single Base Class for All Tests

When using Spring Cloud Contract Verifier in the default (MockMvc), you need to create a base specification for all generated acceptance tests. In this class, you need to point to an endpoint, which should be verified. The following example shows how to do so:

package org.mycompany.tests

import org.mycompany.ExampleSpringController
import com.jayway.restassured.module.mockmvc.RestAssuredMockMvc
import spock.lang.Specification

class MvcSpec extends Specification {
  def setup() {
   RestAssuredMockMvc.standaloneSetup(new ExampleSpringController())
  }
}

If necessary, you can also setup the whole context, as the following example shows:

import io.restassured.module.mockmvc.RestAssuredMockMvc;
import org.junit.Before;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.web.context.WebApplicationContext;

@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT, classes = SomeConfig.class, properties="some=property")
public abstract class BaseTestClass {

    @Autowired
    WebApplicationContext context;

    @Before
    public void setup() {
        RestAssuredMockMvc.webAppContextSetup(this.context);
    }
}

If you use EXPLICIT mode, you can use a base class to initialize the whole tested app, similar to what you might do in regular integration tests. The following example shows how to do so:

import io.restassured.RestAssured;
import org.junit.Before;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.web.server.LocalServerPort;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.web.context.WebApplicationContext;

@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT, classes = SomeConfig.class, properties="some=property")
public abstract class BaseTestClass {

    @LocalServerPort
    int port;

    @Before
    public void setup() {
        RestAssured.baseURI = "http://localhost:" + this.port;
    }
}

If you use the JAXRSCLIENT mode, this base class should also contain a protected WebTarget webTarget field. Right now, the only way to test the JAX-RS API is to start a web server.

9. Using Different Base Classes for Contracts

If your base classes differ between contracts, you can tell the Spring Cloud Contract plugin which class should get extended by the autogenerated tests. You have two options:

Follow a convention by providing a value for packageWithBaseClasses
Provide explicit mapping with baseClassMappings

9.1. By Convention

The convention is such that if you have a contract under (for example) src/test/resources/contract/foo/bar/baz/ and set the value of the packageWithBaseClasses property to com.example.base, then Spring Cloud Contract Verifier assumes that there is a BarBazBase class under the com.example.base package. In other words, the system takes the last two parts of the package, if they exist, and forms a class with a Base suffix. This rule takes precedence over baseClassForTests. The following example shows how it works in the contracts closure:

<plugin>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-contract-maven-plugin</artifactId>
    <configuration>
        <packageWithBaseClasses>hello</packageWithBaseClasses>
    </configuration>
</plugin>

9.2. By Mapping

You can manually map a regular expression of the contract’s package to the fully qualified name of the base class for the matched contract. You have to provide a list called baseClassMappings that consists of baseClassMapping objects that each take a contractPackageRegex to baseClassFQN mapping. Consider the following example:

<plugin>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-contract-maven-plugin</artifactId>
    <configuration>
        <baseClassForTests>com.example.FooBase</baseClassForTests>
        <baseClassMappings>
            <baseClassMapping>
                <contractPackageRegex>.*com.*</contractPackageRegex>
                <baseClassFQN>com.example.TestBase</baseClassFQN>
            </baseClassMapping>
        </baseClassMappings>
    </configuration>
</plugin>

Assume that you have contracts under these two locations:

src/test/resources/contract/com/
src/test/resources/contract/foo/

By providing the baseClassForTests, we have a fallback in case mapping did not succeed. (You can also provide the packageWithBaseClasses as a fallback.) That way, the tests generated from src/test/resources/contract/com/ contracts extend the com.example.ComBase, whereas the rest of the tests extend com.example.FooBase.

10. Invoking Generated Tests

The Spring Cloud Contract Maven Plugin generates verification code in a directory called /generated-test-sources/contractVerifier and attaches this directory to testCompile goal.

For Groovy Spock code, you can use the following:

<plugin>
    <groupId>org.codehaus.gmavenplus</groupId>
    <artifactId>gmavenplus-plugin</artifactId>
    <version>1.5</version>
    <executions>
        <execution>
            <goals>
                <goal>testCompile</goal>
            </goals>
        </execution>
    </executions>
    <configuration>
        <testSources>
            <testSource>
                <directory>${project.basedir}/src/test/groovy</directory>
                <includes>
                    <include>**/*.groovy</include>
                </includes>
            </testSource>
            <testSource>
                <directory>${project.build.directory}/generated-test-sources/contractVerifier</directory>
                <includes>
                    <include>**/*.groovy</include>
                </includes>
            </testSource>
        </testSources>
    </configuration>
</plugin>

To ensure that the provider side is compliant with defined contracts, you need to invoke mvn generateTest test.

11. Pushing Stubs to SCM

If you use the SCM (Source Control Management) repository to keep the contracts and stubs, you might want to automate the step of pushing stubs to the repository. To do that, you can add the pushStubsToScm goal. The following example shows how to do so:

<plugin>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-contract-maven-plugin</artifactId>
    <version>${spring-cloud-contract.version}</version>
    <extensions>true</extensions>
    <configuration>
        <!-- Base class mappings etc. -->

        <!-- We want to pick contracts from a Git repository -->
        <contractsRepositoryUrl>git://https://github.com/spring-cloud-samples/spring-cloud-contract-nodejs-contracts-git.git</contractsRepositoryUrl>

        <!-- We reuse the contract dependency section to set up the path
        to the folder that contains the contract definitions. In our case the
        path will be /groupId/artifactId/version/contracts -->
        <contractDependency>
            <groupId>${project.groupId}</groupId>
            <artifactId>${project.artifactId}</artifactId>
            <version>${project.version}</version>
        </contractDependency>

        <!-- The contracts mode can't be classpath -->
        <contractsMode>REMOTE</contractsMode>
    </configuration>
    <executions>
        <execution>
            <phase>package</phase>
            <goals>
                <!-- By default we will not push the stubs back to SCM,
                you have to explicitly add it as a goal -->
                <goal>pushStubsToScm</goal>
            </goals>
        </execution>
    </executions>
</plugin>

Under [scm-stub-downloader], you can find all possible configuration options that you can pass through the <configuration><contractsProperties> map, a system property, or an environment variable. For instance, you could specify a concrete branch to checkout, instead of the default one

<plugin>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-contract-maven-plugin</artifactId>
    <version>${spring-cloud-contract.version}</version>
    <extensions>true</extensions>
    <configuration>
        <!-- Base class mappings etc. -->

        <!-- We want to pick contracts from a Git repository -->
        <contractsRepositoryUrl>git://https://github.com/spring-cloud-samples/spring-cloud-contract-nodejs-contracts-git.git</contractsRepositoryUrl>
    <contractsProperties>
            <git.branch>another_branch</git.branch>
        </contractsProperties>

        <!-- We reuse the contract dependency section to set up the path
        to the folder that contains the contract definitions. In our case the
        path will be /groupId/artifactId/version/contracts -->
        <contractDependency>
            <groupId>${project.groupId}</groupId>
            <artifactId>${project.artifactId}</artifactId>
            <version>${project.version}</version>
        </contractDependency>

        <!-- The contracts mode can't be classpath -->
        <contractsMode>REMOTE</contractsMode>
    </configuration>
    <executions>
        <execution>
            <phase>package</phase>
            <goals>
                <!-- By default we will not push the stubs back to SCM,
                you have to explicitly add it as a goal -->
                <goal>pushStubsToScm</goal>
            </goals>
        </execution>
    </executions>
</plugin>

12. Maven Plugin and STS

The following image shows an exception that you may see when you use STS:

When you click on the error marker, you should see something like the following:

 plugin:1.1.0.M1:convert:default-convert:process-test-resources) org.apache.maven.plugin.PluginExecutionException: Execution default-convert of goal org.springframework.cloud:spring-
 cloud-contract-maven-plugin:1.1.0.M1:convert failed. at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:145) at
 org.eclipse.m2e.core.internal.embedder.MavenImpl.execute(MavenImpl.java:331) at org.eclipse.m2e.core.internal.embedder.MavenImpl$11.call(MavenImpl.java:1362) at
...
 org.eclipse.core.internal.jobs.Worker.run(Worker.java:55) Caused by: java.lang.NullPointerException at
 org.eclipse.m2e.core.internal.builder.plexusbuildapi.EclipseIncrementalBuildContext.hasDelta(EclipseIncrementalBuildContext.java:53) at
 org.sonatype.plexus.build.incremental.ThreadBuildContext.hasDelta(ThreadBuildContext.java:59) at

To fix this issue, provide the following section in your pom.xml:

<build>
    <pluginManagement>
        <plugins>
            <!--This plugin's configuration is used to store Eclipse m2e settings
                only. It has no influence on the Maven build itself. -->
            <plugin>
                <groupId>org.eclipse.m2e</groupId>
                <artifactId>lifecycle-mapping</artifactId>
                <version>1.0.0</version>
                <configuration>
                    <lifecycleMappingMetadata>
                        <pluginExecutions>
                             <pluginExecution>
                                <pluginExecutionFilter>
                                    <groupId>org.springframework.cloud</groupId>
                                    <artifactId>spring-cloud-contract-maven-plugin</artifactId>
                                    <versionRange>[1.0,)</versionRange>
                                    <goals>
                                        <goal>convert</goal>
                                    </goals>
                                </pluginExecutionFilter>
                                <action>
                                    <execute />
                                </action>
                             </pluginExecution>
                        </pluginExecutions>
                    </lifecycleMappingMetadata>
                </configuration>
            </plugin>
        </plugins>
    </pluginManagement>
</build>

13. Maven Plugin with Spock Tests

You can select the Spock Framework for creating and running the auto-generated contract verification tests with both Maven and Gradle. However, while using Gradle is straightforward, in Maven, you need some additional setup in order to make the tests compile and execute properly.

First of all, you must use a plugin, such as the GMavenPlus plugin, to add Groovy to your project. In GMavenPlus plugin, you need to explicitly set test sources, including both the path where your base test classes are defined and the path were the generated contract tests are added. The following example shows how to do so:

<plugin>
    <groupId>org.codehaus.gmavenplus</groupId>
    <artifactId>gmavenplus-plugin</artifactId>
    <version>1.13.0</version>
    <executions>
        <execution>
            <goals>
                <goal>addSources</goal>
                <goal>addTestSources</goal>
                <goal>compile</goal>
                <goal>compileTests</goal>
            </goals>
        </execution>
    </executions>
    <configuration>
        <testSources>
            <testSource>
                <directory>${project.basedir}/src/test/groovy</directory>
                <includes>
                    <include>**/*.groovy</include>
                </includes>
            </testSource>
            <testSource>
                <directory>
                    ${project.basedir}/target/generated-test-sources/contracts/com/example/beer
                </directory>
                <includes>
                    <include>**/*.groovy</include>
                    <include>**/*.gvy</include>
                </includes>
            </testSource>
        </testSources>
    </configuration>

If you uphold the Spock convention of ending the test class names with Spec, you also need to adjust your Maven Surefire plugin setup, as the following example shows:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-surefire-plugin</artifactId>
    <configuration>
        <detail>true</detail>
        <includes>
            <include>**/*Test.*</include>
            <include>**/*Tests.*</include>
            <include>**/*Spec.*</include>
        </includes>
        <failIfNoTests>true</failIfNoTests>
    </configuration>
</plugin>